1. Field of the Invention
This invention refers to a system to improve the mixing of reacted gases and quench gases and to increase the yields and to reduce the energy consumption in reactors for the heterogeneous synthesis of ammonia and methanol in particular, consisting of: an external shell or pressure-resistant body; an internal cartridge that can form a conduit for the fresh reaction gas flow between the its external wall and the internal wall of the mentioned shell; catalyst baskets placed one above the other; and means to feed unreacted quench gas in order to cool down the reacted gases in the zone between the bottom of the upper catalyst bed and the upper loose surface of the catalyst bed situated below, the above mentioned reaction gas axially traversing at least one of the said catalytic beds.
2. Prior Art
Axial reactors of the above mentioned type were widely used in the pase and are often referred to as "Kellogg"-type reactors. These axial reactors were most often put into service during periods when the cost of energy was very low. With today's higher energy costs it is of great importance, especially in the industrial technology for producing a basic compound as NH3, to improve the efficiency of the synthesis reactor, i.e. to increase as much as possible and at a parity of other conditions, the conversion degree of the reaction gas during the passage through the catalyst beds. This is true not only for newly constructed plants in which the most advanced technology can be applied, but also for plants already in use, in which as explained above, the production costs are strongly influenced by the reactors' performances and must increase along with the rise in energy costs.
Of notable interest are actions or measures adapted to improve the reactors and to increase their efficiency with a consequent reduction in energy consumption.
In prior patents and patent applications, the applicant has suggested reactors of great interest with regard to the yields, operation costs and costs of putting them into production. For example, in the Swiss patent application No. 03238/85, corresponding to U.S. application Ser. No. 859,044, filed May 2, 1986, and No. 02100/85 in particular, an interesting modification to the axial quench-type Kellogg reactor has been proposed to transform them into radial reactors, which are able, among others, to employ smaller granular catalysts notably more active than the larger granular catalysts presently used in axial reactors, with consequent improvement of the reactor performances.
In the continuation of his systematic research in this field, the applicant has been successful in devising and carrying out further improvements to the assett and structure of these reactors with at least one catalytic bed which is axially traversed by the reaction gas; these improvements have proven to be very advantageous in increasing the efficiency of the mixing of the reacted and quench gases, and have thus optimized the general thermal conditions in which the reactions take place. This corresponds to a yield increase and to an energy consumption reduction.
The system, which is the subject of this invention, is characterized by the fact that the mixing of hot reacted gases with cold quench gases takes place in a peripheral zone near the internal cartridge wall.
The reactor, according to the invention, is now characterized by: a toroidal distributor with quench gas outlet near the periphery of the internal cartridge wall and by a double bottom underneath the lower portion of the catalyst bed's grid, for the conveying of the hot reacted gases exiting from the above mentioned bed to the peripheral quench gas outlet zone.
The various aspects and advantages of the invention will better appear from the following description of the preferred, but not limitative embodiments represented in the drawings: